KLK3 and neoplasm: Strikingly, when we performed the opposite experiments by purifying out CD44+/CD44− primary tumor cells from 12 untreated tumor samples (Supplementary Table 2) and analyzing AR and PSA mRNAs in the two populations, we found that the PSA mRNA was preferentially expressed in CD44− HPCa cells in 10 samples whereas AR mRNA expression pattern was more complex with preferential enrichment in CD44− HPCa cells in only 6 samples (Figure 7D).